Probably the most convincing argument for continuing in Afghanistan comes from Jeffrey Simpson's Globe column this morning, "Our Afghan mission must be rooted in realism".
The danger, of course, is that to sell intervention, democratic governments frequently resort to peddling fanciful outcomes, since these come dripping with what people back home want to hear: words and concepts such as "democracy" and "free elections" and "women's rights" and other Western notions, whose adaptation to other cultures is often less than easy.
If the desired outcome in Afghanistan -- the outcome that determines the exit strategy -- is a variant of what Western societies want for themselves, then there is no exit strategy because those changes will not happen, ever.
If the outcome, by contrast, is a series of Afghan regional satrapies with varying degrees of fidelity to a weak central government -- all united, however, in a determination not to allow the Taliban to run the show, then perhaps that more modest outcome could provide a plausible exit strategy. But, of course, that exit strategy is not one people want to hear about in media reports about our brave, freedom-loving and undoubtedly dedicated soldiers.
Note the lack of bullshit, fake appeals to patriotism, and bad poetry ala the Stephen Harper speech.
As usual, you can go to the Globe site:
globeandmail.com : Our Afghan mission must be rooted in realism
...sign in and maybe have your personal information sold to direct marketers, or you can
run "Simpson", "Afghanistan", "Realism" through Google and slip past the sign-in page.